The broad field of the invention is that of thick film conductors for electronic applications. General reference works in this field include "Thick Film Microelectronics," Van Nostrand Reinhold Company, 1971. Thick films are usually formed by screen printing an ink or paste formulated from powdered metals on a non-conductive substrate, typically 96% alumina, and then dried to volatilize vehicle constituents and fired to sinter or fuse the constituents, bonding the film to the substrate. The firing is typically carried out in a belt furnace having a stream of air passing through it for oxidizing the vehicle and removing decomposition products. In the prior art such conductors are made of precious metals in particular gold, silver, platinum, and palladium. Since the amount of metal used in a single unit is not large, the high cost of the precious metals is offset by their advantageous physical properties. However, as the prices of precious metals have increased, interest in thick films made of base metals has increased, since costs can be reduced. Conductor pastes have been introduced to the market in recent years containing such base metals as copper and nickel. Such pastes have been covered in the technical press in such articles as those in Electronic Products, March, 1973, p. 162 and Circuit Manufacturing, November, 1972, p. 48. The pastes heretofore available required firing in a special inert or reducing atmosphere, typically hydrogen. The additional expense and difficulty of such firing makes the development of base metal conductor pastes which can be fired in air or other oxygen containing atmosphere of particular interest. The present invention satisfies that need.